Edible oii containers and method of treating same



Jan. 27, 1959 G. w. HOLMAN 2,

EDIBLE OIL CONTAINERS AND METHOD OF TREATING SAME Filed March 4, 1957 INVENTOR fieqzye iZ/[almzg BY wMG CwGMHt-I wan ATTORNEY;

United States Patent ED IBLE OII CONTAINERS AND METHOD OF TREATING SAMEGeorge W. Holman, Wyoming, Ohio, assignor to The Procter & GambleCompany, Cincinnati, Ohio, a corporation of Ohio Application March 4,1957, Serial No. 643,837

4 Claims. (Cl. 99171) This invention relates to the packaging of liquidglyceride oil products and more particularly to a treated container anda method of treating same for packaging such products to inhibit thedevelopment of rancid odors.

Certain edible oils, notably liquid glycerides subject to oxidativedeterioration and the development of rancidity, such as cottonseed oil,sunflower oil, soybean oil, winterized oil, as well as pourableglyceride shortenings, French dressings and the like, are sometimespackaged in sheet metal or glass containers. Generally the liquid isused in small quantities from time to time by pouring a small amountthrough the spout of the container. Invariably, a drop or two of liquidwill cling to the lip of the pouring spout and subsequently drain downthe exterior surface of the spout. After a relatively short time,usually two or three weeks, the droplets which have collected on theouter container surfaces develop an undesirable rancid odor. Thisundesirable odor is particularly noticeable and most intense on thethreaded portion of the spout. This is because the liquid is forced toassume a relatively thin layer on the threaded portion of the spout asthe cap is threaded thereon resulting in a large surface to volume ratioand more rapid oxidation. In most cases, the undesirable odor developsbefore all the contents of the container'are used. When a consumerdetects the rancid odor, he immediately assumes that the contents in thecontainer have become rancid. In most instances, they have not, becausethe cap on the container prevents rapid oxidation of the product storedwithin the container.

In the past, various ways have been sought to overcome this .problem.Attempts have been made to inhibit the formation of rancid odors bytreating certain externally exposed surfaces of the container withcitric or phosphoric acid. It is well known that these acids inhibit theformation of rancid odors when added to a liquid glyceride product.However, it was discovered that coating the exterior surfaces of acontainer with either citric or phosphoric acid had no inhibiting effecton the formation of rancid odors in the oil draining on such surfaces.In fact, the time at which rancidity developed was accelerated when theexterior spout and adjacent surfaces were coated with either of thesechemicals.

It is an object of the present invention to obviate all of the abovedifficulties.

Another object of the present invention is to coat the exterior surfaceof a container spout and its adjoining surfaces with a substance whichwill inhibit the formation of undesirable rancid odors when a glycerideoil product subject to oxidative deterioration and the development ofrancidity is allowed to remain in contact with such portions of thecontainer.

A further object of this invention is to coat the surfaces of acontainer cap exposed to the contact of a glyceride oil'product subjectto oxidative deterioration and {the development of rancidity with acoating which will in- -"fhibit the formation of undesirable rancidodors when the :"product is allowed to stand in contact wi h. thetreated surfaces of the container cap,

"ice

Briefly and broadly stated, in accordance with the invention, selectedsurfaces of a container or cap or both are coated with a film of analkali metal dihydrogen orthophosphate salt, preferably by applicationof an aqueous solution followed by evaporation of the water to leave asolid film of the alkali metal dihydrogen orthophosphate salt. In sodoing, the time required to develop rancidity of the oil on the treatedsurfaces of the container or cap is tripled or quadrupled as compared tocontainers or caps not so treated.

The invention may be practiced by the use of any alkali metal dihydrogenorthophosphate salt. For convenience, however, NaH PO will be referredto throughout this specification as a preferred example. It will beunderstood that other alkali metal dihydrogen orthophosphate v saltssuch as KH PO can be used wherever reference is made to NaH PO Theinvention can be practiced with glass or metal containers. The film canbe applied with good results to metal containers made of aluminum or tinplated iron,

, for example. However, the invention is especially useful with glass ortin plated containers since these are commonlyused in the trade formarketing liquid or pourable products containing readily oxidizableglyceride oils.

A common form of tin plated iron container is shown,

by way of example, in the accompanying drawing, in

I whichshape having at its upper end a conical shoulder 11 terminatingin the usual threaded spout 12 through which the liquid contents may bedischarged on removal of the internally threaded cap member 15. The capmember may also be tin plated iron, but may be formed of a moldableplastic material.

The odor inhibiting film 16, the thickness of which is exaggerated inthe drawing, forms a coating on the spout 12 and shoulder 11 and on theinner surface of cap member 15, thesolution containing the inhibitingagent having been applied to the container body by immersing its upperportion in the solution as shown in Figure l and dried thereon ashereinbefore described. The container body and/or cap member may, ofcourse, be completely immersed, but this is not ordinarily necessary;preferably only the spout 12 is coated.

It will be appreciated that the container illustrated in the drawing isentirely conventional and that the details thereof form no part of theinstant invention and do not limit the scope of the invention.

' hibit the development of rancid odors in a glyceride spilled on thecoated area. The drying temperature is preferably kept below 200 C. inorder to prevent conversion of the NaH PO to NaPO which is ineffective.Typical of the oils with which the invention can be used are any liquidglycerides subject to oxidative deterioration and development ofrancidity such as cottonseed oil, sunflower oil,

soybean oil, olive oil, and winterized vegetable oils, as

well as liquid or pourable products containing oxidizable glyceride oil,such as French dressing, or any commercially available liquidshortening.

The strength of the NaH PO solution employed for treatment of thecontainer surfaces can be varied between about 5% and about to getsatisfactory results. Erratic results are obtained below about 5%. Aboveabout 20% an objectional white film is formed on the container althoughprotection against the formation of rancid odors is satisfactory.

The NaH PO film can be applied with solution temperatures up to 120 F.At temperatures above 120 F. the film thickness decreases appreciably,reducing the effectiveness of the film ininhibiting formation of rancidodors. However, the 120 F. solution temperature is not to be construedas limiting in any way the maximumtemperature at which the film can beapplied. For instance, a desired film thickness may be achieved at atemperature above 120 F. by applying successive superposed films to thecontainer. It has been determined that an average film thickness between.00030 and 00050 centimeter achieves the objects of the inventionirrespective of the manner in which it is applied.

Cleaning the container before applying a simple solution of NaH PO isusually required in order to form a uniform film which can not be formedon dirty or oily surfaces. Containers when received from a supplierusually have foreign matter and oily films thereon which are depositedin the course of manufacture. However, it may be desirable to eliminatesuch preliminary cleaning step, and it has been found that a continuousfilm of NaH PO can be applied to the surface without preliminarycleaning if a wetting agent is mixed'with the solution. It has beendetermined by experiment that by adding an amount of wetting agent (atleast .1 percent) sufiicient to effect uniform wetting of the containersurface with the NaI-I PO solution, a uniform film can be applied to thesurface, although the preliminary cleaning step has been omitted. Onewetting agent that has been tried with successsful results is the sodiumalkyl sulfate derived bywell known procedures from higher alcoholscontaining predominantly 10-14 carbon atoms, such as the middle cutfraction of alcohols produced by the reduction of coconut oil. Goodresults have been obtained by using a solution containing 10 grams NaHPO and .2 gram of a typical wetting agent consisting essentially ofsodium lauryl sulfate and available commercially under the trademarkDuponol PC, in water to make 100 cc. of solution. Other non-toxicsynthetic wetting agents such as watersoluble salts of higher mono-fattyacid esters of 1,2-dihydroxy propane-3-sulfonic acid (sodium salt of thecoconut oil fatty acid monoester of this sulfonic acid is a specificexample), water-soluble salts of higher fatty acid monoesters of lowermolecular weight hydroxy alkyl sulfonic acids (e. g. oleic acid ester ofthe sodium salt of isethionic acid), water-soluble salts of the higherfatty acid amides of lower molecular amino alkyl sulfonic acids (e. g.sodium salt of coconut oil acid amide of N-methyl taurine) andwater-soluble salts of the higher alcohol esters of sulfo-carboxylicacids (e. g. sodium salt of the lauryl alcohol ester of sulfoaceticacid) can also be substituted.

It is obvious, of course, that .the container cap can be treated in thesame manner as the container in order to,in hibit development of rancidodors attributable to oxidation of oil clinging thereto.

The followingexamples illustrate the improved rancidity inhibitingqualities which can be achieved by the instant invention. They are notbe be construed as limiting in any way the scope of the invention.

Example I.--The time required for developing an objectionable rancidodor was tested by comparing untreated tin plated containers with tinplated containers having a film of NaH PO A 10% solution was made bydissolving 10 grams of Nat-1 1E70 in water with .2 gram wetting agentadded to make 100 cc. of solution. The wetting agent was sodium alkylsulfate derived by the sulfation and subsequent neutralization of higheralcohols con: taining predominantly 10-14 carbon atoms. The spout andshoulder of treated containers were dipped into the solution at roomtemperature and then dried for five minutes at 105 C. Treated anduntreated containers were filled half full of a liquid shorteningproduct predominantly composed of cottonseed oil subject to oxidativedeterioration and the development of rancidity. Four drops of the liquidshortening were deposited on the outer surface of the spout at thethreaded portion of both the treated and untreated containers. Caps wereplaced on the containers and the containers were then subjected to atemperature of 90 F. for an extended period. The containers wererecurrently shaken and the caps were removed every two weeks in order todetermine whether a rancid odor had developed on the container spouts.Some of the oil on the inner surface of the top of the cap would rundown the exterior surface of the container spouts each time they wereinspected. Periodic tests made in this manner determine the elapsed timefrom the begin-' ning of the test-until a moderate to very strong rancidodor developed; The following results were observed.

Time required to develop the rancid odor, weeks Untreated Container 4Treated container 16 fromthebeginning of the test until a rancid odordeveloped, with the time in which rancid odors were detectedon-untreated glass bottles.

The wetting agent in this example can be omitted'from the solution ofNaH PO without substantially modifying the end result provided thesurfaces subjectedto treatment are cleaned prior to the application ofthe solution to enable application of a uniform film.

The improvement noted in Example I can also be shown by using acommercially available olive oil or soybean o-il in place of the liquidshortening product.

Treating solutions containing sodium lauryl sulfate specifically insteadof the alkyl sulfate mixture of this example can be employed withsubstantially the same results.

The container cap can be treated in the same manner as the container ofthis example with marked inhibition of the development of rancid odorsattributable to oxidation of oil clinging thereto.

Example II.Same as Example I except the solution was made using 5 gramsof NaH PO Time required to develop the rancid odor, weeks Untreatedcontainer 2 Treated container Example IIl.-Same as Example I except thesolution was made using 12 grams of NaH PO Time required to develop therancid odor, weeks Untreated container 2 Treated container 16 forvarious reasons be desirable. The coating may, therefore, be said toconsist essentially of the dihydrogen orthophosphate salt, whether ornot additional ingredients, not interfering with the normal inhibitingaction of the salt, are admixed therewith to form the coating.

What is claimed as new is:

1. A container, an edible oil within said container, said oil developinga rancid odor on oxidation, said container comprising a body portionhaving a discharge spout member and a cap member removably seated on andembracing said spout member, said cap member and said spout memberhaving parts which interlock when the cap member is seated on the spoutmember, at least one of said members being provided, on that portion ofits surface contiguous to the other of said members when the cap memberis seated, with a coating of an alkali metal dihydrogen orthophosphatesalt capable of inhibiting the formation of rancid odor.

2. A container, an edible oil within said container, said oil developinga rancid odor on oxidation, said container including a body portionhaving a spout member provided with an externally threaded portion and acap member provided with an internally threaded portion for engaging theexternally threaded portion on said spout member to prevent discharge ofoil from the latter, the threaded portion of at least one of saidmembers being coated with a fihn consisting essentially of an alkalimetal dihydrogen orthophosphate salt.

3. A container having a discharge spout, an edible oil within saidcontainer, said oil being subject to oxidative deterioration, saiddischarge spout being provided with a surface film of an alkali metaldihydrogen orthophosphate salt.

4. The container claimed in claim 3 wherein the film is NaH POReferences Cited in the file of this patent UNITED STATES PATENTS2,356,799 Taylor et al. Aug. 29, 1944 2,785,985 Magill Mar. 19, 1957FOREIGN PATENTS 4 470,518 Great Britain Aug. 17, 1937 1,041,587 FranceJune 3, 1953

2. A CONTAINER, AN EDIBLE OIL WITHIN SAID CONTAINER, SAID OIL DEVELOPINGA RANCID ODOR ON OXIDATION, SAID CONTAINER INCLUDING A BODY PORTIONHAVING A SPOUT MEMBER PROVIDED WITH AN EXTERNALLY THREADED PORTION AND ACAP MEMBER PROVIDED WITH AN INTERNALLY THREADED PORTION FOR ENGAGING THEEXTERNALLY THREADED PORTION ON SAID SPOUT MEMBER TO PERVENT DISCHARGE OFOIL FROM THE LATTER, THE THREADED PORTION OF AT LEAST ONE OF SAIDMEMBERS BEING